The present invention relates to electromyography sensors, and in particular, to wireless electromyography sensors.
Electromyography (EMG) is the measurement of bioelectrical signals resulting from muscle activity. EMG may also be referred to as myography. EMG may be performed for the purpose of identifying or treating medical conditions related to the muscles. Such conditions include Parkinson's disease, amyotrophic lateral sclerosis (ALS), and other conditions. EMG may also be performed for therapeutic purposes. Such purposes include the detection or prevention of repetitive stress injury (RSI), the detection or prevention of carpal tunnel syndrome (CTS), and other purposes.
EMG measurements may be collected by the placement of one or more electrodes on a person. The electrodes may be inserted under the skin for closer proximity to muscles (referred to as injection EMG) or may be placed on the surface of the skin (referred to as surface EMG). The electrodes transmit the measurements to an analysis unit through a wired connection or wirelessly. With more than one electrode, the bioelectrical difference between the electrodes may be measured as indicative of the activity of the muscular tissue between the electrodes.
Many types of wireless EMG sensors currently exist. However, such existing devices have numerous limitations that make them undesirable for many purposes for which EMG is desired.
One such limitation of many existing wireless EMG sensors is that the sensors have a fixed distance between two electrodes. Thus, the size of the sensor determines the nature of measurements that can be made. For example, if the sensor is small and the muscle to be measured is large, the electrodes can measure only a portion of the muscle activity. Conversely, if the sensor is large and the muscle to be measured is small, the electrodes will detect muscle activity beyond the muscle activity of the muscle to be measured.
Another limitation of many existing wireless EMG sensors, similar to the above limitation, is that the sensor is relatively small compared to some muscles for which measurement is desired. The sensor is able to make only small-scale measurements that may not be indicative of the total muscle movement. Small-scale voltage difference readings are prone to interference from other local muscle fiber firing. Whether at a resting state or engaged in activity, muscle motor units are always firing to some extent. This occurs in a disorganized fashion. Therefore, a voltage difference that measures a small distance is not useful, since interference from local disorganized firing occurs. Additionally, those prone to neurological degenerative diseases, such as multiple sclerosis, will not yield significant data, as this local disorganized firing is increased to an exaggerated degree. The signal spikes uncontrollably, and the resulting data graph is useless.
One possible solution would be to have a variety of different sizes of EMG sensors. The most appropriately-sized sensor would then be used according to the size of the muscle to be measured. However, such a solution is impractical. First, it would require a large variety of sizes of EMG sensors corresponding to the wide variety of muscle sizes. One size of EMG sensors would be required for the wrist; another size for the thigh; and so on. Second, it would require a large variety of sizes of EMG sensors corresponding to the wide variety of body types. The thigh EMG sensor for a child would differ from that for a professional basketball player.
A further limitation of many existing wireless EMG sensors is a battery life that is shorter than desirable. Such short battery life leads to the need to replace batteries more often than desired, as well as the recognition that a short battery life results from a device that is wasteful of power.
Thus, there is a need for an improved wireless EMG sensor. There is a need for a wireless EMG sensor that is adaptable to a wide variety of muscle configurations and a wide variety of body types. There is also a need for a wireless EMG sensor that is reusable. Further, there is a need for a wireless EMG sensor that conserves battery power.
The present invention solves these and other problems by providing an adjustable, wireless EMG sensor.